BACKGROUND: Recent phase III studies in hormone refractory prostate cancer (HRPC) showed an improvement in terms of overall survival (OS), objective response (OR) and biochemical response (BR); however, chemotherapy is usually accompanied by negative side effects that determines poor quality of life (QoL) and only marginally improves individual clinical response (ICR) in terms of pain relief and performance status. Ellagic acid is a polyphenol that is found in many species of flowering plants. It is an antioxidant that determines apoptosis, down regulation of IGF-II, activates p21 (waf1/Cip1), mediates the cumulative effect on G1/S transition phase and prevents destruction of p-53 gene by cancer cells. ENDPOINTS: The aim of this study was to assess the effects of ellagic acid support therapy on toxicity, OR, ICR and BR in HRPC patients treated with estramustine phosphate and vinorelbine. MATERIALS AND METHODS: Patients with HRPC were randomly distributed in two study groups: a control group (group A) who underwent chemotherapy with vinorelbine and estramustine phosphate, and an experimental group (group B) where chemotherapy regimen was associated with ellagic acid. RESULTS: The mean number of chemotherapy cycles/patient was 4 (range 3-8 cycles) and 6.5 (range 5-11) in group A and B patients, respectively. A reduction in systemic toxicity, statistically significant for neutropenia, associated with better results in term of OR rate, ICR, and BR were observed in group B compared with group A. On the contrary no significant difference in OS and PFS was detected between groups. CONCLUSIONS: our study suggests that the use of ellagic acid as support therapy reduces chemotherapy induced toxicity, in particular neutropenia, in HRCP patients; however, further studies are required to confirm our results.